The complex of Koguryo Tombs, including several groups and individual tombs – with some 30 individual graves, dates back to the later period of the Koguryo Kingdom, which was one of the most powerful kingdoms ruling northeast China and half of the Korean peninsula (3rd century BC-7th century AD). The tombs are virtually our only known remnants of this colossal culture. Out of more than 10,000 Koguryo tombs discovered in China and Korea so far, only about 90 have wall paintings. Though rare they are perfectly stunning and offer a unique testimony to daily life of this period. Almost a half of these tombs are located within the inscribed complex, and they are believed to have been built for the burial of kings, members of the royal family and the aristocracy. --WHMNet paraphrase from the description at WHC Site, where additional information is available.

Complex of Goguryeo Tombs lies in North Korea. In July 2004 it became the first UNESCO World Heritage site in the country. The site consists of 63 individual tombs from the later Goguryeo kingdom, one of Three Kingdoms of Korea, located in the cities of P'yŏngyang and Namp'o. Goguryeo was one of the strongest kingdoms in the north east of China and the Korean Peninsula between the 5th and 7th centuries AD. The kingdom was founded in the present day area of Northern Korea, and part of Manchuria around 32 BC, and the capital was transferred to P'yŏngyang in AD 427. --Wikipedia. Text is available under the Creative Commons Attribution-ShareAlike License.